Need help with MVVS D7!!!!!!!!!!!!!!!!!!!!
05-23-2017, 08:31 AM
#1
Thread Starter
Need help with MVVS D7!!!!!!!!!!!!!!!!!!!!
Hello all:
As some of you have read, I have been having a large amount of black exhaust residue being produced by my MVVS D7. It was not the fuel or poor needle valve settings. I think that it is being caused by the con rod rubbing on the back plate. However, I have taken steps to determine how I may remedy this problem. Thus far, I have been dumbfounded in my search.
I coated the bp with Prussian Blue and made three additional baskets totaling .0625" to move the bb away from the con rod. This did not help. The rubbing on the cr is about 1/2 inch long on the rod but the area where the crankpin goes through the bottom end, does not touch the bp. Only the rod is rubbing! Is this a sign of a bent rod? I can not see where the bp as been rubbed even after applying the Prussian Blue to the backplate. The PB is transferred to the conrod.
I noticed that the crank pin is about .0625" short of being flush with lower bushing. It also appears to be well away from the crankdisk. The lower rod bushing is protruding about .0625" out of the conrod in the rear. It appears that the conrod should go further towards the crankdisk to cure my problem.
I have carefully broken this engine in on a stand and flown it a couple of times in the air. No electric starter has ever touched this engine. It has never had had been crashed or been crashed. It was always an easy starter. I dislike the idea of taking the engine apart as it has a great p/c fit. However, if I must then I must.
Any suggestion and or suggestions?
Where may I purchase spare parts for this engine?
Be well,
franchi
As some of you have read, I have been having a large amount of black exhaust residue being produced by my MVVS D7. It was not the fuel or poor needle valve settings. I think that it is being caused by the con rod rubbing on the back plate. However, I have taken steps to determine how I may remedy this problem. Thus far, I have been dumbfounded in my search.
I coated the bp with Prussian Blue and made three additional baskets totaling .0625" to move the bb away from the con rod. This did not help. The rubbing on the cr is about 1/2 inch long on the rod but the area where the crankpin goes through the bottom end, does not touch the bp. Only the rod is rubbing! Is this a sign of a bent rod? I can not see where the bp as been rubbed even after applying the Prussian Blue to the backplate. The PB is transferred to the conrod.
I noticed that the crank pin is about .0625" short of being flush with lower bushing. It also appears to be well away from the crankdisk. The lower rod bushing is protruding about .0625" out of the conrod in the rear. It appears that the conrod should go further towards the crankdisk to cure my problem.
I have carefully broken this engine in on a stand and flown it a couple of times in the air. No electric starter has ever touched this engine. It has never had had been crashed or been crashed. It was always an easy starter. I dislike the idea of taking the engine apart as it has a great p/c fit. However, if I must then I must.
Any suggestion and or suggestions?
Where may I purchase spare parts for this engine?
Be well,
franchi
05-23-2017, 10:51 PM
#2
My Feedback: (1)
Hello all:
As some of you have read, I have been having a large amount of black exhaust residue being produced by my MVVS D7. It was not the fuel or poor needle valve settings. I think that it is being caused by the con rod rubbing on the back plate. However, I have taken steps to determine how I may remedy this problem. Thus far, I have been dumbfounded in my search.
I coated the bp with Prussian Blue and made three additional baskets totaling .0625" to move the bb away from the con rod. This did not help. The rubbing on the cr is about 1/2 inch long on the rod but the area where the crankpin goes through the bottom end, does not touch the bp. Only the rod is rubbing! Is this a sign of a bent rod? I can not see where the bp as been rubbed even after applying the Prussian Blue to the backplate. The PB is transferred to the conrod.
I noticed that the crank pin is about .0625" short of being flush with lower bushing. It also appears to be well away from the crankdisk. The lower rod bushing is protruding about .0625" out of the conrod in the rear. It appears that the conrod should go further towards the crankdisk to cure my problem.
I have carefully broken this engine in on a stand and flown it a couple of times in the air. No electric starter has ever touched this engine. It has never had had been crashed or been crashed. It was always an easy starter. I dislike the idea of taking the engine apart as it has a great p/c fit. However, if I must then I must.
Any suggestion and or suggestions?
Where may I purchase spare parts for this engine?
Be well,
franchi
As some of you have read, I have been having a large amount of black exhaust residue being produced by my MVVS D7. It was not the fuel or poor needle valve settings. I think that it is being caused by the con rod rubbing on the back plate. However, I have taken steps to determine how I may remedy this problem. Thus far, I have been dumbfounded in my search.
I coated the bp with Prussian Blue and made three additional baskets totaling .0625" to move the bb away from the con rod. This did not help. The rubbing on the cr is about 1/2 inch long on the rod but the area where the crankpin goes through the bottom end, does not touch the bp. Only the rod is rubbing! Is this a sign of a bent rod? I can not see where the bp as been rubbed even after applying the Prussian Blue to the backplate. The PB is transferred to the conrod.
I noticed that the crank pin is about .0625" short of being flush with lower bushing. It also appears to be well away from the crankdisk. The lower rod bushing is protruding about .0625" out of the conrod in the rear. It appears that the conrod should go further towards the crankdisk to cure my problem.
I have carefully broken this engine in on a stand and flown it a couple of times in the air. No electric starter has ever touched this engine. It has never had had been crashed or been crashed. It was always an easy starter. I dislike the idea of taking the engine apart as it has a great p/c fit. However, if I must then I must.
Any suggestion and or suggestions?
Where may I purchase spare parts for this engine?
Be well,
franchi
could the rod be in backwards? The front facing conrod bearing should be slightly counterbored to match the fillet on the crankpin.
05-24-2017, 04:11 AM
#3
Thread Starter
Hello Gazimoto:
BINGO! I think that you may be on to something! I bought this engine "NEW" from a dealer who sold Diesel engines and supplies. I have not disassembled the engine. I will check the rod.
Thank you very much,
franchi
BINGO! I think that you may be on to something! I bought this engine "NEW" from a dealer who sold Diesel engines and supplies. I have not disassembled the engine. I will check the rod.
Thank you very much,
franchi
05-24-2017, 05:02 AM
#4
My Feedback: (1)
Otherwise the shaft may be displaced a bit towards the backplate, and/or the rear race may not be correctly seated in the crankcase. While the rod/piston/liner is out, gently heat the engine up to just under 100 degrees C and tap the crankshaft forward sharply a few times. I have made a brass punch to do this. One end has a step machined in it and the smaller end just fits into the induction hole. Reassemble and check the crankpin clearance.
05-24-2017, 11:14 AM
#5
Thread Starter
Hello Gazimoto:
It is not the crank pin rubbing but the area between the lower rod journal and about 25 m up the rear face of the rod. After I reassemble the engine with the Prussian Blue on the back plate, there is a transfer of PB onto the rod. Everything feels free and there is no sign of friction any place. I hope that I am able to slide the bronze bushing back into the rod! It is sticking out about .0625". I have never had the bronze bushing slide out of the hole in the rod!
If the rod is indeed in backwards, does this engine have circlips holding the gudgen in place? If there are circlips to RR, could I just rotate the piston 180 degrees providing there are no ports or notches on the piston? I have less that good times with circlips. Lol I have no idea how bad the p&c fit will be after I do this.
It is not the crank pin rubbing but the area between the lower rod journal and about 25 m up the rear face of the rod. After I reassemble the engine with the Prussian Blue on the back plate, there is a transfer of PB onto the rod. Everything feels free and there is no sign of friction any place. I hope that I am able to slide the bronze bushing back into the rod! It is sticking out about .0625". I have never had the bronze bushing slide out of the hole in the rod!
If the rod is indeed in backwards, does this engine have circlips holding the gudgen in place? If there are circlips to RR, could I just rotate the piston 180 degrees providing there are no ports or notches on the piston? I have less that good times with circlips. Lol I have no idea how bad the p&c fit will be after I do this.
05-24-2017, 05:11 PM
#7
Thread Starter
Hi Gazimoto:
I was wrong about the bushing sliding our of the rod. After disassembling the engine, the rod that was not being flush with the end of the crankpin. Instead, the rod is more narrow at the big end than the crankpin is long. This means that crankpin protrudes about .0625" out of the rear of the rod. The rod looks like it was from a damaged engine. There are many deep gouges and places on the outside of the big end that look like they banged on the insides of the crankcase. Perhaps this rod came from a different engine like ST. I have never seen an engine where the crank pin was too long for width of the eye of the rod. Perhaps I should start looking for MVVS rod! I am beginning to think that I was sold an engine that was not new but had been made up of spare and in one case, damaged parts. There was no box, instructions etc. like one would get with new engine.
I filed the sides of the rod a bit to make sure that it does not hit the crank disk. There was a cut on the side of the rod made by crank disk like it had been milled. This may have been what was driving the rod into the back plate. I will check this fit in the morning.
Thanks for taking the time to consider my dilemma
Cheers,
Leomat.
I was wrong about the bushing sliding our of the rod. After disassembling the engine, the rod that was not being flush with the end of the crankpin. Instead, the rod is more narrow at the big end than the crankpin is long. This means that crankpin protrudes about .0625" out of the rear of the rod. The rod looks like it was from a damaged engine. There are many deep gouges and places on the outside of the big end that look like they banged on the insides of the crankcase. Perhaps this rod came from a different engine like ST. I have never seen an engine where the crank pin was too long for width of the eye of the rod. Perhaps I should start looking for MVVS rod! I am beginning to think that I was sold an engine that was not new but had been made up of spare and in one case, damaged parts. There was no box, instructions etc. like one would get with new engine.
I filed the sides of the rod a bit to make sure that it does not hit the crank disk. There was a cut on the side of the rod made by crank disk like it had been milled. This may have been what was driving the rod into the back plate. I will check this fit in the morning.
Thanks for taking the time to consider my dilemma
Cheers,
Leomat.
05-24-2017, 05:18 PM
#8
My Feedback: (1)
Hi Gazimoto:
I was wrong about the bushing sliding our of the rod. After disassembling the engine, the rod that was not being flush with the end of the crankpin. Instead, the rod is more narrow at the big end than the crankpin is long. This means that crankpin protrudes about .0625" out of the rear of the rod. The rod looks like it was from a damaged engine. There are many deep gouges and places on the outside of the big end that look like they banged on the insides of the crankcase. Perhaps this rod came from a different engine like ST. I have never seen an engine where the crank pin was too long for width of the eye of the rod. Perhaps I should start looking for MVVS rod! I am beginning to think that I was sold an engine that was not new but had been made up of spare and in one case, damaged parts. There was no box, instructions etc. like one would get with new engine.
I filed the sides of the rod a bit to make sure that it does not hit the crank disk. There was a cut on the side of the rod made by crank disk like it had been milled. This may have been what was driving the rod into the back plate. I will check this fit in the morning.
Thanks for taking the time to consider my dilemma
Cheers,
Leomat.
I was wrong about the bushing sliding our of the rod. After disassembling the engine, the rod that was not being flush with the end of the crankpin. Instead, the rod is more narrow at the big end than the crankpin is long. This means that crankpin protrudes about .0625" out of the rear of the rod. The rod looks like it was from a damaged engine. There are many deep gouges and places on the outside of the big end that look like they banged on the insides of the crankcase. Perhaps this rod came from a different engine like ST. I have never seen an engine where the crank pin was too long for width of the eye of the rod. Perhaps I should start looking for MVVS rod! I am beginning to think that I was sold an engine that was not new but had been made up of spare and in one case, damaged parts. There was no box, instructions etc. like one would get with new engine.
I filed the sides of the rod a bit to make sure that it does not hit the crank disk. There was a cut on the side of the rod made by crank disk like it had been milled. This may have been what was driving the rod into the back plate. I will check this fit in the morning.
Thanks for taking the time to consider my dilemma
Cheers,
Leomat.
05-25-2017, 01:03 PM
#10
Thread Starter
Hello All:
I reassembled the engine and ran it on a test stand. The first two runs were very good. Easy starting and NO black residue in the exhaust. As a matter of fact, there was no white smoke in the exhaust. ????? The third run began to produce a slight dark exhaust residue emitting from the exhaust. I removed the back plate and did not see any rub pattern on it. I removed all traces of prior contact with the rod from the back plate. This will aid me in monitoring any contact with the con rod. The con rod did not display any sign of contact with the crank disk. I will check again with the Prussian Blue trick when I get a chance.
The engine is much easier to hand start and the p&c fit seems to be good.
Many thanks to all who responded with help!
Be well my fiends,
Franchi
I reassembled the engine and ran it on a test stand. The first two runs were very good. Easy starting and NO black residue in the exhaust. As a matter of fact, there was no white smoke in the exhaust. ????? The third run began to produce a slight dark exhaust residue emitting from the exhaust. I removed the back plate and did not see any rub pattern on it. I removed all traces of prior contact with the rod from the back plate. This will aid me in monitoring any contact with the con rod. The con rod did not display any sign of contact with the crank disk. I will check again with the Prussian Blue trick when I get a chance.
The engine is much easier to hand start and the p&c fit seems to be good.
Many thanks to all who responded with help!
Be well my fiends,
Franchi
05-26-2017, 07:57 AM
#11
Thread Starter
More information concerning the MVVS.
I ran the engine a bit today before I installed it back into the Tom Tom. Here is what I happily discovered.
The engine will hand start cold by increasing the compression and choking for one turn of the prop. Hot starts require only one choked turn of the prop. I thought that I had very little trouble with Diesel engines in the 70's. This engine was defective since day one. The exhaust had a very light brown colour bout the same as my ST G20/ 15D engines. There was very little if any white smoke. I am a very happy person now!
Cheers,
Franchi
I ran the engine a bit today before I installed it back into the Tom Tom. Here is what I happily discovered.
The engine will hand start cold by increasing the compression and choking for one turn of the prop. Hot starts require only one choked turn of the prop. I thought that I had very little trouble with Diesel engines in the 70's. This engine was defective since day one. The exhaust had a very light brown colour bout the same as my ST G20/ 15D engines. There was very little if any white smoke. I am a very happy person now!
Cheers,
Franchi
05-26-2017, 03:11 PM
#13
Thread Starter
Hi Gaz:
I was very careful not to do that as I was hoping to get the piston back into the cylinder close to where it had been prior disassembly. Lots of luck! The rod was symmetrical so I just filed a bit off of the area that was rubbing on the crank disk. I am quite certain that the rod in the engine was not the correct on as the crank pin is still a bit longer than the large hole in the rod is wide. I have a good supply of ST rods but the gudgen SP? wrist pin, on the ST is 4mm and the MVVS is a bit smaller. I was impressed at how well the innards were designed and made. This engine now runs like I have been told that a Diesel is supposed to run. Easy starting!!!!!!!!!!!!!!!!!!!!!!!
Be well my friend.
I was very careful not to do that as I was hoping to get the piston back into the cylinder close to where it had been prior disassembly. Lots of luck! The rod was symmetrical so I just filed a bit off of the area that was rubbing on the crank disk. I am quite certain that the rod in the engine was not the correct on as the crank pin is still a bit longer than the large hole in the rod is wide. I have a good supply of ST rods but the gudgen SP? wrist pin, on the ST is 4mm and the MVVS is a bit smaller. I was impressed at how well the innards were designed and made. This engine now runs like I have been told that a Diesel is supposed to run. Easy starting!!!!!!!!!!!!!!!!!!!!!!!
Be well my friend.
